1. Field of Invention
The present invention relates to a display system including an organic electroluminescent material and relates to an electronic device.
2. Description of Related Art
Recently, color display systems having a luminescent layer including a luminescent material, such as an organic fluorescent material being disposed between a pixel electrode (anode) and a cathode have been developed. Particularly, an organic EL display system including a luminescent material, such as an organic electroluminescent (organic EL) material has been developed.
A conventional display system (organic EL display system) will now be described with reference to the accompanying drawing. FIG. 13 shows a wiring structure of the conventional display system. The conventional display system has a plurality of scanning lines 901, a plurality of signal lines 902 extending in the direction that intersects the scanning lines 901, and a plurality of light-emitting power-supply lines 903 extending in parallel to the signal lines 902. In the conventional display system, a pixel region A is arranged for each intersecting point of each scanning line 901 and each signal line 902.
Each signal line 902 is connected to a data side-driving circuit 904 equipped with a shift register, a level shifter, a video line, and an analog switch. Each scanning line 901 is connected to scan-side driving circuits 905 and 905′ each equipped with another shift register and another level shifter.
Each pixel region A can include a switching thin-film transistor 912, in which scanning signals are transmitted to the gate electrode through the scanning line 901; a capacitor Cap for storing pixel signals transmitted from the signal line 902 through the switching thin-film transistor 912, a current thin-film transistor 923 in which the pixel signals stored in the capacitor Cap are transmitted to the gate electrode, a pixel electrode 911 to which a driving current is supplied from each light-emitting power-supply line 903 when the pixel electrode 911 is electrically connected to the light-emitting power-supply line 903 through the current thin-film transistor 923, and a light-emitting element 910 disposed between the pixel electrode 911 and a cathode 913. The cathode 913 is connected to a cathode power-supply circuit 931.
The light-emitting element 910 has three types of light-emitting sub-elements including a red light-emitting sub-element 910R, a green light-emitting sub-element 910G, and a blue light-emitting sub-element 910B, which are arranged in a stripe pattern.
Red, green, and blue light-emitting power-supply lines 903R, 903G, and 903B are connected to the red, green, and blue light-emitting sub-elements 910R, 910G, and 910B, respectively, through each current thin-film transistor 923 and are connected to a light-emitting power-supply circuit 932. Since the light-emitting element 910 needs different driving potentials depending on the color, each light-emitting power-supply line is connected to a corresponding color light-emitting sub-element.
According to the above configuration, when each scanning line 901 is energized to turn each switching thin-film transistor 912 on, a potential applied to each signal line 902 at that time is stored in the capacitor Cap and the current thin-film transistor 923 is turned on or turned off depending on the state of the capacitor Cap. Subsequently, a current is supplied from the red, green, and blue light-emitting power-supply lines 903R, 903G, and 903B to the pixel electrode 911 through the channel of the current thin-film transistor 923, and a driving current is supplied to the cathode 913 through the light-emitting element 910. The light-emitting element 910 emits light depending on an applied potential.